Chrome: Google Chrome has a built-in speech recognition system, but you can only use it in certain places. Dictation is a webapp that uses Chrome's speech recognition engine, but allows you to dictate much larger chunks of text right inside a simple webapp.

From the Dictation webapp, you can either click the microphone, or hit Ctrl+Shift+. (period) to activate dictation mode. Then, you simply need to start speaking. Dictation recognizes "new line" to create a new paragraph, and "delete everything" to start over. Once your text is dictated, you can hop right in and correct any mistakes right inside the app. When you're done you can copy and paste the text over to your favorite text editing program. If you've ever wanted to play around with the idea of dictation, but didn't want to spend money on specialized software, Dictation is a free alternative that works well.